build: install clang-format only if not exists (#9667)

refactor: install clang-format only if not exists

Signed-off-by: mikutas <23391543+mikutas@users.noreply.github.com>

Signed-off-by: mikutas <23391543+mikutas@users.noreply.github.com>

Makefile

@@ -299,11 +299,13 @@ $(GOPATH)/bin/goimports:
 	go install golang.org/x/tools/cmd/goimports@v0.1.7
 
 /usr/local/bin/clang-format:
+ifeq (, $(shell which clang-format))
 ifeq ($(shell uname),Darwin)
 	brew install clang-format
 else
 	sudo apt-get install clang-format
 endif
+endif
 
 pkg/apis/workflow/v1alpha1/generated.proto: $(GOPATH)/bin/go-to-protobuf $(PROTO_BINARIES) $(TYPES) $(GOPATH)/src/github.com/gogo/protobuf
 	# These files are generated on a v3/ folder by the tool. Link them to the root folder